This sentence is using an image found in old agriculture. The words ‘a tough row to hoe’ refer to the rows of crops in the field. A hoe is a tool that a farmer uses to remove weeds. The word ‘tough’ means difficult.
短時間內要做完那一切工作，真難啊！
用 a tough row to hoe 來形容非常吃重（吃力）的一件事，意義很貼切；此處用的是從前農業時代，農人以手握鋤鬆土（或除草）的辛苦情景，其「意象」相當鮮明。